Patent Article 1WO pamphlet 0198301Patent Article 2WO pamphlet 03020313Patent Article 3WO pamphlet 02092068Patent Article 4WO pamphlet 0218395Patent Article 5WO pamphlet 02076995Patent Article 6Japanese Patent Laid-OpenPublication No. Hei 2003-137894Patent Article 7WO Pamphlet 03040097Patent Article 8WO Pamphlet 02064616Patent Article 9WO Pamphlet 02062389Patent Article 10WO Pamphlet 03051876Patent Article 11WO Pamphlet 03061567Patent Article 12WO Pamphlet 03062248Patent Article 13WO Pamphlet 03062252Patent Article 14WO Pamphlet 03073986Non-Patent Article 1Y. Takuma et al., Mol. Cell.Endocrinol., 177, 3(2001)Non-Patent Article 2Y. Igarashi, Ann, N.Y. Acad. Sci.,845, 19(1998)Non-Patent Article 3H. Okazaki et al., Biochem.Biophs. Res. Commun., 190, 1104(1993)Non-Patent Article 4S. Mandala et al., Science, 296,346(2002)Non-Patent Article 5V. Brinkmann et al., J. Biol.Chem., 277, 21453(2002)
Sphingosine-1-phosphate (referred to simply as S1P, hereinafter), which was previously considered a mere intermediate product in the metabolism of sphingosine, has proven to have an ability to facilitate cell growth and regulate cell motility. Studies have now shown that S1P, a previously unknown lipid mediator, is involved in a wide range of physiological actions, including apoptisis, modification of cell morphology and vascular contraction (Non-Patent Article 1 and Non-Patent Article 2). The lipid acts both as an intracellular second messenger and as an intercellular mediator; its role as an intercellular mediator has been particularly intensively studied. S1P induces signal transduction via a family of cell membrane G-protein-coupled receptors designated as Edg (which stands for Endothelial Differential Gene) (Non-Patent Article 1 and Non-Patent Article 3). Currently known subtypes of S1P receptors are Edg-1, Edg-3, Edg-5, Edg-6 and Edg-8, which are also referred to as S1P1, S1P3, S1P2, S1P4 and S1P5, respectively.
Many studies of these S1P receptors suggest that S1P receptor modulators, which bind to these receptors and act as agonists or antagonists of S1P receptors, are effective against a broad spectrum of diseases. For example, compounds that act on Edg-5 have been shown effective against arteriosclerosis, renal fibrosis, pulmonary fibrosis and hepatic fibrosis (Patent Article 1). Compounds that act on Edg-1, Edg-3 or Edg-5 have been shown to be effective therapeutic or prophylactic agents against various respiratory diseases, including chronic bronchial asthma, diffuse pulmonary hamartoangiomyomatosis, adult respiratory distress syndrome (ARDS), chronic obstructive pulmonary disease (COPD), interstitial pneumonia, idiopathic interstitial pneumonia, lung cancer and hypersensitivity pneumonitis (Patent Article 2). In addition, compounds that act as Edg-1 agonists have been shown to be effective therapeutic or prophylactic agents for peripheral vascular diseases, such as arteriosclerosis obliterans, thromboangiitis obliterans, Buerger's disease and diabetic neuropathy, septicemia, angiitis, nephritis, pneumonia, cerebral infarction, myocardial infarction, edema, arteriosclerosis, varicose veins, such as piles, anal fissure and anal fistula, dissecting arterial aneurysm, stenocardia, DIC, pleuritis, congestive heart failure, multiple organ failure, bed sore, burn, ulcerative colitis, Crohn's disease, heart transplantation, kidney transplantation, skin transplantation, liver transplantation, bone marrow transplantation, osteoporosis, chronic hepatitis, hepatic cirrhosis, chronic renal failure and glomerulosclerosis (Patent Article 3). Furthermore, compounds that act as agonists of S1P receptors have been shown to modulate the migration of leukocytes (Non-Patent Article 4 and Non-Patent Article 5). Moreover, the derivatives mentioned in the aforementioned Non-Patent Articles have been shown effective not only against various organ transplants and GVHD, but also against autoimmune diseases, such as rheumatoid arthritis, lupus nephritis, systemic lupus erythematosus, Hashimoto's disease, multiple sclerosis, myasthenia gravis, type I and type II diabetes and Crohn's disease, allergic diseases, such as atopic dermatitis, allergic rhinitis, allergic conjunctivitis, allergic contact dermatitis, and inflammatory diseases, such as inflammatory bowel disease and ulcerative colitis (Patent Article 4 and Patent Article 5). Phosphoric acid derivatives similar to what are described in Patent Articles 4 and 5 and act as antagonists of S1P receptors are described in Patent Article 6. Other S1P receptor modulators are disclosed in Patent Articles 7, 8, 9 and 10.
In the course of the studies to develop compounds that have an ability to modulate S1P receptors, which are involved in the onset of various disorders, the present inventors have drawn the attention to aminophosphonic acid derivatives having different structures from previously known compounds and have made an effort in searching for novel modulators of S1P receptors. Quite recently, S1P receptor agonists having an amino group along with a phosphonic acid unit were disclosed in Patent Articles 11, 12 and 13. Each of these compounds has a structure in which the amino group is integrated in their linking backbone. This structure differs from the structure of the compounds of the present invention, which essentially has the form of β-aminophosphonic acid or γ-aminophosphonic acid in which an amino group exists on the linking backbone. Patent Article 14 describes similar compounds but the compounds of the present invention are not included.